721017161 has 4 divisors (see below), whose sum is σ = 721322112. Its totient is φ = 720712212.

The previous prime is 721017151. The next prime is 721017181. The reversal of 721017161 is 161710127.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 721017161 - 2¹⁰ = 721016137 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 721017161.

It is not an unprimeable number, because it can be changed into a prime (721017151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 148901 + ... + 153666.

It is an arithmetic number, because the mean of its divisors is an integer number (180330528).

Almost surely, 2^721017161 is an apocalyptic number.

It is an amenable number.

721017161 is a deficient number, since it is larger than the sum of its proper divisors (304951).

721017161 is a wasteful number, since it uses less digits than its factorization.

721017161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 304950.

The product of its (nonzero) digits is 588, while the sum is 26.

The square root of 721017161 is about 26851.7627168125. The cubic root of 721017161 is about 896.7028164663.

Adding to 721017161 its reverse (161710127), we get a palindrome (882727288).

The spelling of 721017161 in words is "seven hundred twenty-one million, seventeen thousand, one hundred sixty-one".